Preparation of 17alpha-fluoroprogesterone and intermediates therein



United States Patent Oflice 3,118,882 Patented Jan. 21, 1964 3,118,882 PREPA-RA'HGN F 17wFLU9ROPROGESTERONE AND INTERMEDIATES THEREIN Romano Deghenghi, Westrnount, Quebec, Canada, as-

signer to Americanv Home Products Corporation, New York, N .Y., a corporation of Delaware No Drawing. Filed Feb. 7, 1962', S'er..No. 171,582 Claims priority, application Canada Feb. 16, 1961 7 Claims. (Cl. 260239.55)

The present invention relates to l7a-fluoroprogesterone, to a methodfor its preparation, and to the preparation of intermediates useful in its synthesis.

At least one attempt at introducing fluorine into the 170L-pOSltlOI1 of progesterone hasbeen made, but this attempt remained unsuccessful (E. L. Shapiro et al. I. Am. Chem. Soc., vol 81, p. 6483 (1959 The introduction of the 17a-fluoro group into ll-oxygenated steroids ofthe pregnane series has been described by E. B. Hershberg et al. (J. Am. Chem. Soc. vol. 82, p. 3691 (1960)), but the use of anhydrous hydrogen fluoride in that synthesis results in the formation of large amounts of undesirable by-products with concomitantly poor yields of the desired 17a-fluoro-corticoids- Attempts to apply the reaction with anylidrous hydrogen fluoride to compounds of the pregnene series lacking an oxygen function in the ll-position, resulted in obtaining only unreacted starting materials.

The applicant has now found that introduction of fluorine into the 170t-pOSlt1OIl of progesterone may be effected smoothly in the following manner. 17u-bromo-progesterone is stirred in solution in an inert Water-miscible solvent, in the presence of cyanide ions, and of a butter, for instance potassium acetate at a temperature between 0 C. and the boiling point of the mixture, preferably at room temperature. Under those conditions the 3-keto- A -group remains unaffected and only 20-cyano-l7,8,20 epoxy-4-isopregnen-3-one is obtained in good yields. A suitable solvent may be, for example, a lower alkanol, a lower ether, for instance ethylene glycol monomethyl ether, a lower cyclic ether, for example dioxane, dimethylformamide, or dimethylsulfoxide.

The latter compound suspended in aqueous hydrofiuoric acid containing from five to fifty-five percent hydrogen fluoride and stirred at temperatures between 0 C. and 100 C., preferably at room temperature, adds smoothly the elements of hydrogen fluoride to give 20- cyano-17a-fluoro-20-hydroxy-4-pregnen-3-one in excellent yields.

When dissolving the latter cyanohydrin in a polar water-miscible solvent and refluxing one to twenty-four hours it loses readily the elements of hydrogen cyanide and l7a-fluoroprogesterone is obtained in very good yields. In this reaction small amounts of organic bases such as, for example pyridine, collidine, or triethylamine may also be added to effect complete removal of hydrogen cyanide. A suitable polar water-miscible solvent may be, for example, a lower alkanol, a lower ketone, a lower ether such as, for example, methyl Cellosolve, a lower cyclic ether such as, for example, dioxane, dimethylformamide or dimethylsulfoxide, preferably a lower alkanol with a boiling point between 60 C. and 100 C.

Alternatively, the removal of the elements of hydrogen cyanide may be effected by heating 17 a-fluoro-4-pregnen- 3-one-20-cyanohydrin in an organic base, obtaining 17ozfluoroprogesterone, as above, but in inferior yields. A suitable organic base may be, for example, pyridine or collidine.

17a-fluoroprogesterone is useful as an orally active progestational agent and also as an intermediate in the synthesis of 17a-fluoro-corti'coids, recentlydescribed by E. B. Hershberg'et al. (J. Am. Chem. Soc., 82, 3691" (1960)).

11?, as described for example in the textbook by L. F.

Fieser and M. Fieser, Steroids, Reinhold: Publishing Corp., New'York, 1959, pages 672-673. ll-oxygenated l'loc-llllOIO-COXBPOUHd may then: be acetoxylated in position 21 by the methoddescribed-by H. J". Ringold and G. Stork (I. Am. Chem. Soc., 80, 250 (1958.).),.and the21- acetoxy group may be removed by conventional means. to obtain the desired 17u-fluoro-corticoids.

The reactions of the invention may be exemplified: as follows:

no :03. e 0

Preferred embodiments of the invention are illustrated further in the following examples.

EXAMPLE 1 ZO-Cyano-J 713,20-Ep0xy-4-Is0pregnen-3-One To 17ot-bromoprogesterone (20 grams) in 1,200 ml. commercial ethanol, was added a mixture of 5.8 grams KCN and 8.5 grams of CH COOK in ml. of Water.

The resulting solution was stirred at room temperature for twenty-four hours. At the end of this time 3.0 grams of the title compound crystallized out and was collected on a filter. The alcoholic filtrate was poured in excess volume of ice water and the precipitate collected on a filter and washed with water. The combined dried precipitates weighed 17.0 grams representing crude cyano epoxide, M.P. 230-240 C.

A sample was crystallized three times for analysis, M.P. 246-250 C. (methanol), [a] +21.3 (1% in chloroform), A IlltflX. 241 mu (6 17,400). 'y CHCl :225O cm.- (CEN), A -3-ketone at 1665 and 1620 cm.-

Analysis confirmed the empiric formula C H NO Required: C, 77.84; H, 8.61; N, 4.13%. Found: C, 77.81; H, 8.46; N, 4.06%.

EXAMPLE 2 1 7 Ot-F luoroprogesterone ZO-cyano-175,20-epoxy-4-isopregnen-3-one, 2.4 grams, was suspended in 30 grams of 48% aqueous HF and stirred at room temperature for one hour. The resulting oily substance was taken up in ether and washed to neu trality with sodium bicarbonate solution and water. Evaporation of the solvent gave 2.45 grams of a white Such synthesis may be carried out by oxidiz ing 17a-fiuoroprogesterone microbiologically in position 3 solid, which crystallized from ether, M.P. 2l0-211 C. dec.

When this substance, representing crude 20-cyano-17ufluoro-20-hydroxy-4-pregnen-3-one, was dissolved in warm aqueous methanol, HCN gas was evolved and 17afluoroprogesterone crystallized out of the mixture in about 80% yield.

Alternatively the cyanohydrin (1 gram) was refluxed for one hour in 5 ml. of collidine. After usual working up 0.98 gram of a yellow oil was obtained which, upon chromatography on silica gel, gave 17a-fiuoroprogesterone in about 40% yield. M.P. 176-179 C.

Analysis confirmed the empiric formula C H O F. Required: C, 75.87; H, 8.79; F, 5.71. Found: C, 76.08; H, 8.76; F, 5.90.

'y CI-ICl 1715 cm.- (20 C=O), A -3 ketone at 1665 and 1620 cm.- A max. mu. (6 18,000).

I claim:

1. The process which comprises reacting ZO-cyano- 17B,20-epoxy-4-isopregnen-3-one in a heterogeneous phase with aqueous hydrogen fluoride, thereby forming 20-cyano-17u-fiuoro-20-hydroxy-4-pregnen-3-one.

2. The process which comprises dissolving 20-cyano- 17a-fiuoro-20-hydroxy-4-pregnen-3-one in a polar waterrniscible solvent, thereby forming 17a-fluoroprogesterone, and recovering said latter compound.

3. The process for the preparation of 20-cyano-17B, 20-epoxy-4-isopregnen-3 0ne which comprises subjecting 17tx-bromoprogesterone to the action of cyanide ions and a buffer in inert solvent solution, and recovering the resulting reaction product.

4. The process of the preparation of l7a-fluoroprogesterone which comprises reacting 20-cyano-17B,20- epoxy-4-isopregnen-3-one in a heterogeneous phase with aqueous hydrogen fluoride, thereby to form 20-cyano- 17a-fluoro-20-hydroxy-4-pregnen-3-one, recovering the latter and dissolving it in a polar water-miscible sol-vent, thereby causing the formation of 17a-fluoroprogesterone; and recovering the latter compound.

5. The process for the preparation of 17u-11UOI'0PI0- gesterone which comprises subjecting 17a-bromoprogcsterone to the action of cyanide ions in the presence of a buffer in inert solvent solution to form 20-cyano-17fl, 20-epoxy-4-isopregnen-3-one; reacting the latter with aqueous hydrogen fluoride, thereby to form 20-cyano' 17a-fluoro-20-hydroxy-4-pregnen-3-one; recovering the latter and dissolving it in a polar water-miscible solvent, thereby causing the formation of 17a-fluoroprogesterone; and recovering said latter compound.

6. ZO-cyano-17a-fiuoro-20-hydroxy-4-pregnen-3-one.

7. ZO-cyano-17,8,20-epoxy-4-isopregnen-3-one.

References Cited in the file of this patent UNITED STATES PATENTS Lincoln et a1. Nov. 19, 1957 

5. THE PROCESS FOR THE PREPARATON OF 17-A-FLUOROPROGESTERONE WHICH COMPRISES SUBJECTING 17A-BROMOPROGESTERONE TO THE ACTION OF CYANIDE IONS IN THE PRESENCE OF A BUFFER IN INERT SOLVENT SOLUTION TO FORM 20-CYANO-17B, 20-EPOXY-4-ISOPREGNEN-3-ONE; REACTING THE LATTER WITH AQUEOUS HYDROGEN FLUORIDE, THEREBY TO FORM 20-CYANO17A-FLUORO-20-HYDROXY-4-PREGNEN-3-ONE; RECOVERING THE LATTER AND DISSOLVING IT IN A POLAR WATER-MISCIBLE SOLVENT, THEREBY CAUSING THE FORMATION OF 17A-FLUOROPROGESTERONE; AND RECOVERING SAID LATTER COMPOUND. 